Aeronautical engineering: A continuing bibliography with indexes (supplement 271)

This bibliography lists 666 reports, articles, and other documents introduced into the NASA scientific and technical information system in October, 1991. Subject coverage includes design, construction and testing of aircraft and aircraft engines; aircraft components, equipment and systems; ground support systems; and theoretical and applied aspects of aerodynamics and general fluid dynamics

Aeronautical engineering: A continuing bibliography with indexes (supplement 218)

This bibliography lists 469 reports, articles, and other documents introduced into the NASA scientific and technical information system in September, 1987

Aeronautical Engineering. A continuing bibliography, supplement 115

This bibliography lists 273 reports, articles, and other documents introduced into the NASA scientific and technical information system in October 1979

Proceedings of the 14th Annual Precise Time and Time Interval (PTTI) Applications Planning Meeting

Developments and applications in the field of frequency and time are addressed. Specific topics include rubidium frequency standards, future timing requirements, noise and atomic standards, hydrogen maser technology, synchronization, and quartz technology

Aeronautical engineering: A cumulative index to a continuing bibliography (supplement 235)

This publication is a cummulative index to the abstracts contained in Supplements 223 through 234 of Aeronautical Engineering: A Continuing Bibliography. The bibliographic series is compiled through the cooperative efforts of the American Institute of Aeronautics and Astronautics (AIAA) and the National Aeronautics and Space Administration (NASA). Seven indexes are included -- subject, personal author, corporate source, foreign technology, contract number, report number and accession number

NASA Tech Briefs, May/June 1986

Topics discussed include: NASA TU Services; New Product Ideas; Electronic Components and Circuits; Electronic Systems; Physical Sciences; Materials; Computer Programs; Machinery; Fabrication Technology; Mathematics and Information Sciences; Life Sciences

Resonant DC link converters and their use in rail traction applications

Conventional 'hard switching' converters suffer from significant switching loss due to thesimultaneous imposition of high values of current and voltage on the devices during commutation.Resonant converters offer a solution to this problem. A review of resonant circuit topologies ispresented, which includes a summary of the interference problems which may occur when usingpower converters in the rail traction environment. Particular attention is given to the ResonantDC Link Inverter (RDCLI) which shows a great deal of pronuse using currently availabledevices.The frequency domain simulation of RDCLIs is discussed as a means of rapidly evaluatingcircuit behaviour, especially in relation to modulation strategies. A novel modulation strategy isproposed for Resonant DC Link Inverters, based on a procedure known as Simulated Annealingwhich allows complex harmonic manipulations such as han-nonic minimisation, to be performed.This is despite the fact that RDCLIs are constrained to use Discrete Pulse Modulation wherebyswitch commutations are restricted to specific moments in time. The modulation algorithms wereverified by use of a low-power test rig and the results obtained are compared against theoreticalvalues. Details of the hardware implementation are also included.A single-phase pulse-converter input stage is described which may be incorporated into theResonant DC Link Inverter topology. This input stage also benefits from soft-sVVItching andallows four-quadrant operation at any desired power factor. A modulation scheme based onSiMulated Annealing is proposed for the pulse-converter, to achieve hannomc control whilst alsosynchronising with the supply wavefon-n. Practical results are presented and compared with thoseobtained by simulation and calculation.Finally the design of Resonant DC Link Converters is discussed and reconunendations made forthe choice of resonant components based on the minimisation of overall losses. Comparisons aremade between hard-switching and soft-switching converters in terms of loss and harmonicperformance, in an attempt to quantify the benefits which may be obtained by the application ofsoft-switching

Deep Space Gateway Concept Science Workshop : February 27–March 1, 2018, Denver, Colorado

The purpose of this workshop is to discuss what science could be leveraged from a deep space gateway, as well as first-order determination of what instruments are required to acquire the scientific data.Institutional Support, National Aeronautics and Space Administration, Lunar and Planetary Institute, Universities Space Research Association ; Executive Committee, Ben Bussey, HEOMD Chief Scientist, NASA Headquarters, Jim Garvin, Goddard Space Flight Center Chief Scientist, Michael New, NASA Headquarters, Deputy AA for Research, SMD, Paul Niles, Executive Secretary, NASA Johnson Space Center, Jim Spann, MSFC Chief Scientist, Eileen Stansbery, Johnson Space CenterPARTIAL CONTENTS: Deep Space Gateway as a Deployment Staging Platform and Communication Hub of Lunar Heat Flow Experiment--Lunar Seismology Enabled by a Deep Space Gateway--In-Situ Measurements of Electrostatic Dust Transport on the Lunar Surface--Science Investigations Enabled by Magnetic Field Measurements on the Lunar Surface--Enhancing Return from Lunar Surface Missions via the Deep Space Gateway--Deep Space Gateway Support of Lunar Surface Ops and Tele-Operational Transfer of Surface Assets to the Next Landing Site--Development of a Lunar Surface Architecture Using the Deep Space Gateway--The Deep Space Gateway: The Next Stepping Stone to Mar